package com.ruijixiang.leetcode.hot100;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class leetcode0015 {
    public List<List<Integer>> threeSum(int[] nums){
        List<List<Integer>> res=new ArrayList<>();
        if(nums.length<3) return res;
        Arrays.sort(nums);
        int n=nums.length;
        for(int i=0;i<n;i++){
            // 去重
            if(i>0 && nums[i]==nums[i-1]) continue;
            int left=i+1,right=n-1;
            while(left<right){
                int sum=nums[i]+nums[left]+nums[right];
                if(sum<0){
                    left++;
                }else if(sum>0){
                    right--;
                }else{
                    res.add(Arrays.asList(nums[i],nums[left],nums[right]));
                    while(left<right && nums[left]==nums[left+1]){
                        left++;
                    }
                    while(left<right && nums[right]==nums[right-1]){
                        right--;
                    }
                    left++;
                    right--;
                }
            }
        }
        return res;
    }
}
